This invention relates to testing of microwave transistors under high power (non-linear) conditions using automatic microwave impedance tuners in order to synthesize reflection factors (or impedances) at the input and output of said transistors at the fundamental and various harmonic frequencies. This method of testing is commonly called “load pull”.
Modern design of high power microwave amplifiers, oscillators and other active components used in various communication systems requires accurate knowledge of the active device's (microwave transistor's) characteristics. In such circuits, it is insufficient and inaccurate for the transistors operating at high power in their highly non-linear regions and close to saturation, to be described using analytical or numerical models. Instead the devices must be characterized using specialized test setups under the actual operating conditions.